
Lamarck’s
Theory
*Lamarck attempted to
explain evolution he said…
 Physical features increase in
size when used, decrease
when not used
 Changes pass to offspring
 Incorrect theory, but heading
in right direction


Charles
Darwin



*Darwin traveled aboard the
HMS Beagle on his way to the
Galapagos Islands
Found evidence that species
gradually change over time
Ex: found fossils of extinct
armadillos that were different
than present day armadillos
(BIG DEAL!)
Darwin suggested that the
ancestors of Galapagos
species migrated to the
islands from South America
long ago, & changed after
they arrived
*Population: consists of
ALL the individuals of a
species that live in a
specific area and can
interbreed
THINK – PAIR – SHARE
How does the shape of each finches beak affect the
survival of their species?
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___________________________________________
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
*Natural
Selection
Those with favorable
behavioral or physical traits
will be more likely to survive
and reproduce
 Number of those with
favorable traits will increase
 Adaptation: Features that
are common in a population
because it provides a
selective advantage

Think – Pair – Share
•In terms of natural selection, what is occurring in the picture
below?
•Later in time, what do you believe the approximate ratio of
green to tan beetles will be?
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_________________________________________________
_________________________________________________
______________________

Updating
Darwin’s
Ideas




Scientists now know genes are
responsible for inherited traits
Certain traits become more
common when more and more
individuals carry them
Natural selection causes an
increase/decrease of certain
traits!
Mutation and recombination
gives variation

Updating
Darwin’s
Ideas

2. Populations of same species
living in different locations can
evolve differently
◦ *Reproductive Isolation- species
can no longer interbreed due to
geographic separation

Updating
Darwin’s
Ideas


Kaibab squirrel – North Rim of
Grand Canyon
Abert squirrell – South Rim
The Tempo of Evolution
• *Punctuated
Equilibrium- there
• *Gradualismare periods of rapid
evolution is a
change separated by
gradual change over
periods of little to no
time
change in species
Modeling Natural Selection
• Grab 4 pieces of paper
• On separate pieces write the words
“live”, “die”, “reproduce”, and
“mutate”
Modeling Natural Selection
• What factors determined if someone
survived in this model?
• How does this model explain natural
selection?
Fossil Record

Evidence
of
Evolution
 2.
Anatomy and
Development
◦ A. Vestigial structuresevidence of an organism’s
evolutionary past
 Ex: Whale’s hind limbs

Evidence
of
Evolution
 2.
Anatomy and
Development
◦ B. Homologous Structuressimilarities in structures
suggests common ancestry
 Ex: Forelimb bones between
many species
Which layer of
fossils is the
oldest?
A
B
C
D
E
Section 1 & 2 Whiteboard
Review
• Give one example of a piece of
evidence in evolution
• What does the presence of hind leg
remnants in the whale indicate?
Section 1 & 2 Whiteboard
Review
• Species that share a distant common
ancestor
•
•
•
•
(a) have many amino acid sequence differences
(b) have few amino acid sequence differences
(c) have identical amino acid sequences
(d) are not represented by the fossil record
Section 1 & 2 Whiteboard
Review
• According to Darwin, evolution
occurs
• (a) in response to use or disuse of a
characteristic
• (b) by punctuated equilibrium
• (c) by natural selection
• (d) within an individuals lifetime
Section 1 & 2 Review
• Most scientists agree that
•
•
•
•
(a) Earth is about 3.5 million years old
(b) life is new on Earth
(c) living organisms share ancestry
(d) fossils do not exist
Section 1 & 2 Review
•
•
•
•
•
A vestigial structure is one that is
(1) similar to structure in other species
(2) reduced in size and useless
(3) an embryological structure
(4) a characteristic of vertebrate
Section 1 & 2 Review
• The similarity of certain structures,
called homologous structures
suggest that organisms
•
•
•
•
(a) all grow at different rates
(b) life for a long time
(c) evolved slowly
(d) have a common ancestor
Section 1 & 2 Review
• A species that lacks the variation
necessary to adapt to a changing
environment is more likely to
• (1) develop many mutated cells
• (2) become extinct over time
• (3) begin to reproduce sexually
• (4) develop resistance to diseases
Section 1 & 2 Review
• A particular species of shark normally reproduces
sexually. In captivity, it was found that a female
could also reproduce asexually. One negative
result from asexual reproduction is
• (1) increased gene recombinations
• (2) increased number of males produced
• (3) decreased number of eggs used
• (4) decreased biodiversity within the species
Section 1 & 2 Review
• Which statement is best supported by the theory of
evolution?
• (1) Genetic alterations occur every time cell
reproduction occurs.
• (2) The fossil record provides samples of every
organism that ever lived.
• (3) Populations that have advantageous
characteristics will increase in number
• (4) Few organisms survive when the environment
remains the same.


Section 3

Natural
Selection

A quote from Darwin’s book
reads “Can we doubt…that
individuals having any
advantage, however slight, over
others, would have the best
chance of surviving and
procreating their kind?”
Question: What is Darwin saying
here?





The process of natural selection has four main
points
All populations have genetic variation
The environment presents challenges to
successful reproduction
Individuals tend to produce more offspring than
the environment can support
Individuals better able to cope with environment
leave more offspring
Your group is going to create a poster on
various examples of Evolution in 25 min.
 1. Using pages 289 – 292 you must have
the following sections in your poster
◦ Example of Natural Selection
◦ Evolution of Darwin’s Finches
◦ Formation of a New Species
 While you’re making your poster, make
sure you can answer the questions in your
packet that goes along with each section
 If you have extra time, look online for your
own examples of evolution!


Evidence
of
Evolution

1. Fossil Record
◦ E. Record is incomplete
◦ F. Fossils are rare, remains must
immediately be buried by sediment
◦ G. Fossils commonly found near
water, volcanoes
◦ H. Few fossils in forests, mountains,
grasslands or deserts

Evidence
of
Evolution

1. Fossil Record
◦ I. Paleontologists study fossils,
sequencing them in age, by dating
the rocks

Evidence
of
Evolution
 2.
Anatomy and
Development
◦ C. Embryology- vertebrate
embryos possess structural
similarities
 Tail
 Buds that develop into limbs
 Gill like pouches (pharyngeal
pouches)
Evolution
• Evidence
of
Evolution
• 3. Biological Molecules
– Proteins- closely related
species have fewer
differences in amino acid
sequences



Relate how the fossil record provides evidence
that evolution has occurred
State how comparing the amino acid sequence of
a protein can provide evidence that evolution has
taken place
Describe how comparing the anatomy of living
species provides evidence of evolution

Key
factors in
natural
selection
 1.
All populations have
genetic variation (slight
differences)

Key
factors in
natural
selection
 2.
Environment presents
challenges to successful
reproduction
◦ Dictates direction and amount of change
◦ Determines whether one trait or another is
more advantageous

Key
factors in
natural
selection
 3.
Individuals
overproduce offspring
(more than environment
can handle) to ensure the
survival of some

Key
factors in
natural
selection
 4.
Individuals better able
to cope with environment
leave more offspring

Examples
of natural
selection:
Antibiotic
Resistanc
e




Tuberculosis could be treated by
antibiotics isoniazid and rifampin
Rifampin-resistant strain of bacteria
evolved through mutation rendering
the antibiotic useless against it
Difference between 2 strains was one
single nucleotide
Antibiotic resistance- when antibiotics
kill susceptible bacteria, and resistant
bacteria begin to reproduce rapidly

Examples
of natural
selection:
Darwin’s
Finches






Collected 9 species of finches
Differed only in bill shape/size
Evolved from common ancestor
Changes occurred as different
populations adapted to different food
sources
Dry season- bird with massive beaks
better at feeding (could crack open
larger, dryer seeds), and thus,
produced more offspring
Wet season- all birds equally
successful

Examples
of natural
selection:
Formation
of New
Species


Divergence- accumulation of
differences between groups (leads to
speciation- formation of new species)
Subspecies- develop when members
of a species live in different
environments and develop different
adaptations
◦ May become so different from one another,
that interbreeding ceases

What
prevents
members
of a
species
from
mating?





Geographic Isolation
Differing reproduction rates
Physical differences
preventing mating
No attraction to one
another
Hybrid offspring infertile or
not suited to environment





List four elements of natural selection
Describe the mechanism that causes population
changes in antibiotic resistant bacteria
Identify what caused the change in the finch’s
beaks as seen in the Grants’ study
Describe how speciation takes place
What factor caused the beaks of finches on the
Galapagos islands to enlarge over generations?






Evolution Simulations by PBS
Becoming Human Documentary
Evolution Lab
PBS: Evolution Videos
Human Evolution Animations
Evolution Video and Interactive Links